// brushess motor: synchronous mode
#define AIN1 0               // coil A, input pin 1
#define AIN2 1               // coil A, input pin 2
#define BIN1 2               // coil B, input pin 1
#define BIN2 3               // coil B, input pin 2

void setup() {
  // set coil control pins as Teensy outputs
  for (int i = 0; i < 8; ++i) pinMode(i, OUTPUT);
}

void set_coil(int in1, int v1, int in2, int v2) {
  digitalWrite(in1, v1);
  digitalWrite(in2, v2);
  digitalWrite(in1+4, v1);
  digitalWrite(in2+4, v2);
  delay(15);
}
void loop(){
  set_coil(AIN1,LOW,AIN2,HIGH);
  set_coil(BIN1,HIGH,BIN2,LOW);
  set_coil(AIN1,HIGH,AIN2,LOW);
  set_coil(BIN1,LOW,BIN2,HIGH);
}